Block copolymer, method of forming the same, and method of forming pattern

ABSTRACT

A block copolymer is provided. The block copolymer according to an exemplary embodiment includes a first block represented by Chemical Formula 1 and a second block represented by Chemical Formula 2: 
                         
wherein COM1 and COM2 are independently selected from a polystyrene moiety, polymethylmethacrylate moiety, polyethylene oxide moiety, polyvinylpyridine moiety, polydimethylsiloxane moiety, polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 is hydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenyl group, a is 1 to 50, R2 is hydrogen or an alkyl group with 1 to 10 carbon atoms, and b is 1 to 50.

This application claims priority to Korean Patent Application No.10-2013-0003439, filed on Jan. 11, 2013, and all the benefits accruingtherefrom under 35 U.S.C. §119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND

(a) Technical Field

The present disclosure relates to a block copolymer, a method of formingthe same, and a method of forming a pattern.

(b) Description of the Related Art

Recently, there has been interest in the scientific community to developmethods to form a pattern having a minute line width using a blockcopolymer. The pattern formation method controls molecular weight of theblock copolymer to form a pattern of various sizes, and controls amolecular weight ratio of the blocks in the block copolymer to form apattern of various shapes.

A block copolymer is a polymer comprising two or more polymer blocksconnected to each other through a covalent bond. In a diblock copolymer,which is the simplest structure of a block copolymer, two polymer blockshaving different properties are connected to each other to form onepolymer. The two polymer blocks that are connected to each other may beeasily phase-separated due to different material properties, and theblock copolymer may be finally self-assembled to form a nanostructure.In a linear block copolymer, phase-separation and self-assembly within ashort process time can provide a pattern having a size of several tensof nanometers, however it is difficult to provide a pattern having aperiod of more than 100 nm from a self-assembly process because thephase-separation time is long.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY

The present disclosure provides a block copolymer, a method of makingthe block copolymer, and a pattern formation method having an increasedphase-separation speed achieved by minimizing entanglement betweenpolymers.

A block copolymer according to an exemplary embodiment of the presentdisclosure includes a first block represented by Chemical Formula 1 anda second block represented by Chemical Formula 2:

wherein COM1 and COM2 are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 ishydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenylgroup, a is 1 to 50, R2 is hydrogen or an alkyl group with 1 to 10carbon atoms, and b is 1 to 50.

The block copolymer may comprise a block represented by Chemical FormulaBC comprising a first block represented by Chemical Formula 1 and asecond block represented by Chemical Formula 2:

wherein COM1 and COM2 are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 ishydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenylgroup, x is 10 to 500, a is 1 to 50, R2 is hydrogen or an alkyl groupwith 1 to 10 carbon atoms, y is 10 to 500, and b is 1 to 50.

In Chemical Formula 1, COM1 may comprise a group represented by ChemicalFormula 3, and in Chemical Formula 2, COM2 may comprise a grouprepresented by Chemical Formula 4:

wherein Ph is a phenyl group and Me is methyl, n is 10 to 1000, m is 10to 1000, and * means a point of attachment.

The block copolymer is represented by Chemical Formula 5:

wherein Ph is a phenyl group, Me is methyl, x is 10 to 500, y is 10 to500, n is 10 to 1000 and m is 10 to 1000.

The first block and the second block may be connected to each otherrandomly.

The block copolymer can be made, for example, by using a materialrepresented by Chemical Formula 6

wherein OTBS is a tert-butyldimethylsilyloxy group.

The material of Chemical Formula 6 may be synthesized based on ReactionEquation 1:

wherein TBSCl is tert-butyldimethylsilyl chloride, and OTBS istert-butyldimethylsilyloxy group.

The block copolymer is made by polymerizing a first macromer representedby Chemical Formula 7 or Chemical Formula 7-1 and a second macromerrepresented by Chemical Formula 8 by a ring opening metathesispolymerization method:

wherein Ph is a phenyl group, Me is methyl, a is 1 to 10, n is 10 to1000, b is 1 to 10, and m is 10 to 1000.

The first macromer represented by Chemical Formula 7 may be synthesizedbased on Reaction Equation 2:

wherein OTBS is a tert-butyldimethylsilyl oxy group, Ph is phenyl, and nis 10 to 1000.

The second macromer may be synthesized based on Reaction Equation 3:

wherein Ph is phenyl, Me is methyl, OTBS is tert-butyldimethylsilyl oxygroup, and m is 10 to 1000.

A Grubbs catalyst may be present during the polymerization of the firstmacromer and the second macromer.

The first macromer represented by Chemical Formula 7-1 may besynthesized based on Reaction Equation 4:

wherein Ph is phenyl, and n is 10 to 1000.

A pattern formation method according to an exemplary embodiment of thepresent disclosure includes: coating a block copolymer comprising afirst block and a second block on a substrate comprising a motherpattern layer to form a polymer thin film; selectively removing oneblock of a first block and a second block from the polymer thin film;and etching the mother pattern layer by using the polymer thin film fromwhich one block is removed as a mask.

The polymer thin film may be treated with ultraviolet rays or heat.

A block copolymer according to another exemplary embodiment of thepresent disclosure includes: a first block represented by COM A inStructural Formula A; a second block represented by COM B in StructuralFormula A; and a random block inserted between the first block and thesecond block and represented by RBC in Structural Formula A:

In the Structural Formula A, COM A and COM B are independently selectedfrom polystyrene, polymethylmethacrylate, polyethylene oxide,polyvinylpyridine, polydimethylsiloxane, polyferrocenyldimethylsilane,and polyisoprene, and RBC is a group in which at least two unit blocksare randomly copolymerized.

COM A may be a group comprising polystyrene, and COM B may be a groupcomprising polymethylmethacrylate.

The block copolymer may be represented by Chemical Formula B:

wherein a molecular weight of Chemical Formula B is 10,000 to 1,000,000,1 and n are 10 to 10,000, m is 5 to 2000, x is 10 to 500, y is 10 to 500and a unit block represented by

and a unit block represented by

in RBC are randomly copolymerized.

The block copolymer can be synthesized, for example, based on ReactionEquation A.

A pattern formation method according to an exemplary embodiment of thepresent disclosure includes: coating the block copolymer represented byStructural Formula A on a substrate including a mother pattern layer toform a polymer thin film; selectively removing one block of a firstblock and a second block from the polymer thin film; and etching themother pattern layer by using the polymer thin film from which one blockis removed as a mask.

The polymer thin film may be treated with ultraviolet rays or heat.

According to an exemplary embodiment of the present disclosure, byforming a bottle-brush type block copolymer described herein, theentanglement phenomenon of the polymer is minimized by the presence ofside chains such that the phase separation speed is increased and themain chain is spread. Accordingly, process time to form a pattern byusing such a block copolymer may be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

A description of the figures, which are meant to be exemplary and notlimiting, is provided in which:

FIG. 1 and FIG. 2 are photos showing a phase-separation phenomenon of avertical lamella structure of a bottle-brush type block copolymercomprising a first block represented by Formula 1 and a secondrepresented by Formula 2.

FIG. 3 is a schematic diagram of an exemplary block copolymer ofStructural Formula A.

FIG. 4 is a cross-sectional view of a hardening state of the blockcopolymer of FIG. 3 after coating the block copolymer on a substrate.

FIG. 5 and FIG. 6 are photos showing a phase-separation phenomenon of avertical lamella structure of a block copolymer of Structural Formula A.

FIG. 7 to FIG. 10 are cross-sectional views of a coated substrateillustrating an exemplary pattern formation method.

FIG. 11 is a perspective view of a pattern formed by the patternformation method illustrated in FIG. 7 to FIG. 10, and

FIG. 12 is a cross-sectional view of the pattern of FIG. 11 taken alongthe line XII-XII.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsare shown. However, it is to be understood that the disclosure is notlimited to the disclosed embodiments, but, on the contrary, is intendedto cover various modifications. As those skilled in the art wouldrealize, the described embodiments may be modified in various differentways, all without departing from the spirit or scope of the presentdescription.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. It will be understood that when an elementsuch as a layer, film, region, or substrate is referred to as being “on”another element, it can be directly on the other element or interveningelements may also be present. Like reference numerals designate likeelements throughout the specification.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer, or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. The term“or” means “and/or.” As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list. It will be further understood that theterms “comprises” and/or “comprising,” or “includes” and/or “including”when used in this specification, specify the presence of statedfeatures, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof. Spatially relative terms, such as“beneath,” “below,” “lower,” “above,” “upper” and the like, may be usedherein for ease of description to describe one element or feature'srelationship to another element(s) or feature(s) as illustrated in thefigures. It will be understood that the spatially relative terms areintended to encompass different orientations of the device in use oroperation in addition to the orientation depicted in the figures. Forexample, if the device in the figures is turned over, elements describedas “below” or “beneath” other elements or features would then beoriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below. Thedevice may be otherwise oriented (rotated 90 degrees or at otherorientations) and the spatially relative descriptors used hereininterpreted accordingly.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this general inventive conceptbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand the present disclosure, and will not be interpreted in an idealizedor overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

Reaction conditions and reagents shown in the reaction equations areillustrative and it is appreciated that other reaction conditions andreagents may be selected without undue experimentation.

A First Embodiment is a Bottle-Brush Type Block Copolymer as FurtherDescribed Below.

A block copolymer according to an exemplary embodiment of the presentdisclosure comprises a first block represented by Chemical Formula 1 anda second block represented by Chemical Formula 2.

Here, COM1 and COM2 are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 ishydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenylgroup, a is 1 to 50, R2 is hydrogen or an alkyl group with 1 to 10carbon atoms, and b is 1 to 50. The first block and the second block maybe connected to each other randomly.

A block copolymer according to an exemplary embodiment of the presentdisclosure comprises a block represented by Chemical Formula BCcomprising a first block represented by Chemical Formula 1 and a secondblock represented by Chemical Formula 2:

Here, COM1 and COM2 are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 ishydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenylgroup, x is 10 to 500, a is 1 to 50, R2 is hydrogen or an alkyl groupwith 1 to 10 carbon atoms, y is 10 to 500, and b is 1 to 50.

As shown in Chemical Formula 1 and Chemical Formula 2, the blockcopolymer according to the present exemplary embodiment is abottle-brush type block copolymer having a structure comprising a mainchain and a side chain connected to the main chain. Accordingly, anentanglement phenomenon between polymers is minimized by the presence ofthe side chain such that a phase generation speed is increased and aspread of the main chain is generated. In this way, although a length ofthe main chain may be shorter as compared with a linear block copolymer,realization of the phase-separation having a large period (i.e.,distance between the repetition of the physical structure) is possibleby the spread of the main chain, and a shorter process time may berealized by the minimization of the entanglement phenomenon.

In a specific embodiment, COM1 in Chemical Formula 1 may comprise agroup represented by Chemical Formula 3, and COM2 in Chemical Formula 2may comprise a group represented by Chemical Formula 4.

Here, n is 10 to 1000 and m is 10 to 1000. Ph means a phenyl group, Memeans a methyl group, and * means a point of attachment.

The block copolymer according to the present exemplary embodiment may berepresented by Chemical Formula 5.

Here, n is 10 to 1000 and m is 10 to 1000. x is 10 to 500 and y is 10 to500. Ph means a phenyl group and Me means a methyl group.

Next, a method of making a bottle-brush type block copolymer accordingto the present exemplary embodiment will be described.

The bottle-brush type of block copolymer according to an exemplaryembodiment of the present disclosure can be made in the presence of acompound or material of Chemical Formula 6.

Here, a is 1 to 10, and OTBS is a tert-butyldimethylsilyloxy group. Theinitiator material according to the present exemplary embodimentincludes an end having a functional group (GOH) such as —OTBS inChemical Formula 6 such that a hydroxyl group may be generated orinduced when synthesizing a macromer that will be described later.

The compound of Formula 6 according to the present exemplary embodimentmay be synthesized based on Reaction Equation 1.

Here, TBSCl is tert-butyldimethylsilyl chloride, THF is tetrahydrofuran,OTBS is a tert-butyldimethylsilyloxy group, DEAD is diethylazodicarboxylate, PPh₃ is triphenylphosphine, MeLI is methyllithium, andEt₂O is diethyl ether.

The bottle-brush type block copolymer according to the present exemplaryembodiment may be formed by polymerizing a first macromer represented byChemical Formula 7 or Chemical Formula 7-1 and a second macromerrepresented by Chemical Formula 8 by a ROMP (ring opening metathesispolymerization) method.

Here, a is 1 to 10, n is 10 to 1000, b is 1 to 10, and m is 10 to 1000.Ph is a phenyl group and Me is a methyl group. During the polymerizationof the first macromer and the second macromer, a Grubbs catalyst may beused. The Grubbs catalyst used is preferably a third generation Grubbscatalyst as shown below.

wherein Mes represents a mesitylene group, and Ph is a phenyl group.

The first macromer represented by Chemical Formula 7 and the secondmacromer according to the present exemplary embodiment may besynthesized based on Reaction Equation 2 and Reaction Equation 3respectively. As shown in Reaction Equation 2 or Reaction Equation 3, inthe preparation of the first macromer, a compound represented byChemical Formula 6 is used in the second step, and in the preparation ofthe second macromer, a compound represented by Chemical Formula 6 isused in the first step. The compound of Formula 6 can be used tosynthesize the first macromer or the second macromer via negative ionpolymerization.

Here, THF is tetrahydrofuran, TBAF is tetrabutylammonium fluoride, MeOHis methanol, DCC is dicyclohexylcarbodiimide, DPTS is pyridiniump-toluenesulfonate, n is 10 to 1000, and Ph is a phenyl group.

Here, THF is tetrahydrofuran, TBAF is tetrabutylammonium fluoride, DCCis dicyclohexylcarbodiimide, DPTS is pyridinium p-toluenesulfonate, andm is 10 to 1000.

In other embodiment, the first macromer represented by Chemical Formula7-1 may be a material synthesized based on Reaction Equation 4.

Here, s-BuLi is sec-butyllithium, DCC is dicyclohexylcarbodiimide, DPTSis pyridinium p-toluenesulfonate, Ph is a phenyl group, n is 10 to 1000,and m is 10 to 1000.

The bottle-brush type block copolymer according to the present exemplaryembodiment may be synthesized based on Reaction Equation 5.

Here, Ph is a phenyl group, Me is methyl, x is 10 to 500, y is 10 to500, n is 10 to 1000, and m is 10 to 1000.

Experimental Example 1

A neutralization layer is formed on a silicon substrate, and thebottle-brush type block copolymer comprising a first block representedby Formula 1 and a second block represented by Formula 2 is mixed withpropylene glycol methyl ethyl acetate (“PGMEA”) to prepare a solutioncontaining 5 wt % of the block copolymer. The solution is coated on theneutralization layer. Next, solvent annealing is performed for 40minutes at a temperature of 21° C. Next, a heat treatment (thermalannealing) is performed for 60 minutes at a temperature of 240° C.

Referring to FIG. 1, FIG. 1 is a vertical lamella structure of the blockcopolymer having random directivity. It may be confirmed thatphase-separation of the block copolymer is achieved.

Experimental Example 2

After forming the neutralization layer as described in ExperimentalExample 1, guide patterns having a width of about 1.5 μm are formed, andthe bottle-brush type of block copolymer comprising a first blockrepresented by Formula 1 and a second block represented by Formula 2 iscoated between the guide patterns. The rest of the process is performedthe same as in Experimental Example 1.

Referring to FIG. 2, FIG. 2 is a vertical lamella structure of ananoline shape aligned between a guided pattern. It may be confirmedthat the phase-separation of the block copolymer is generated therebyforming a linear pattern well.

Next, a block copolymer according to another exemplary embodiment willbe described, in particular a linear block copolymer embodiment isdescribed.

The linear block copolymer according to an exemplary embodiment of thepresent disclosure includes a first block represented by COM A inStructural Formula A, a second block represented by COM B in StructuralFormula A, and a random block inserted between the first block and thesecond block and represented by RBC in Structural Formula A.

Here, COM A and COM B are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, and RBC isa group in which at least two unit blocks are randomly copolymerized.

It is preferable that COM A is a group comprising a polystyrene moiety,and COM B is a group comprising a polymethylmethacrylate moiety inStructural Formula A.

FIG. 3 is schematic diagram of a block copolymer according to anexemplary embodiment of the present disclosure.

Referring to FIG. 3, the block copolymer according to the presentexemplary embodiment is a linear block copolymer in which a random blockRBC is inserted between a first block NB1 and a second block NB2. Therandom block RBC has an effect of spreading the tangled chain. Withoutbeing bound by theory, in particular, the reason that thephase-separation is generated in the copolymer comprising the linkedfirst block and the second block is based on a repulsive force betweenthe first block and the second block. Accordingly, in the random blockRBC, a monomer forming the first block and a monomer forming the secondblock are randomly mixed such that the repulsing monomers tend to spreadand to not be mixed with each other in the random block RBC. Also, thefirst block and the second block tend to spread and to not be mixed withthe random block RBC. Accordingly, the period may be increased in thephase-separation pattern of the block copolymer and the fastphase-separation may be realized.

FIG. 4 is a cross-sectional view of a hardening state of the blockcopolymer of FIG. 3 after coating the block copolymer on a substrate.

Referring to FIG. 4, if the block copolymer according to an exemplaryembodiment of the present disclosure is hardened by the heat treatment,the phase-separation is performed such that a structure having anaverage period T of less than about 100 nm is formed.

The linear block copolymer according to the present exemplary embodimentmay be a block copolymer represented by Chemical Formula B.

Here, a molecular weight of Chemical Formula B is 10,000 to 1,000,000, 1and n are 10 to 10,000, m is 5 to 2000, x is 10 to 500, y is 10 to 500,and a unit block represented by

and a unit block represented by

in RBC are randomly copolymerized.

Next, a method of making the linear block copolymer including the randomblock according to the present exemplary embodiment will be described.

The linear block copolymer according to an exemplary embodiment of thepresent disclosure is synthesized by Reaction Equation A.

Here, AIBN is 2,2′-azobis(2-methylpropionitrile), and RAFT is reversibleaddition-fragmentation chain transfer polymerization.

Experimental Example 3

FIG. 5 shows a vertical lamella structure having random directivity.

A neutralization layer is formed on a silicon substrate, and threesamples of the block copolymer, of which a volume fraction of the randomblock is respectively 8%, 12%, and 15% in the three samples is mixedwith the PGMEA and is coated on the neutralization layer. Next, thermalannealing is performed for 12 hours at a temperature of 250° C. As aresult, compared with the linear block copolymer without the randomblock, the period (i.e., distance between the repetition of the physicalstructure) is respectively increased by 28%, 67%, and 70%.

FIG. 5 shows a phase-separation phenomenon in which the linear blockcopolymer of which the volume fraction of the random block is 8% isthermal-treated, and it may be confirmed that the phase-separation ofthe block copolymer is generated well.

Experimental Example 4

After forming the neutralization layer as described in ExperimentalExample 3, guide patterns having a width of about 0.8 μm are formed andthe linear block copolymer is coated between the guide patterns. Therest of the process is performed the same as in Experimental Example 3.

Referring to FIG. 6, FIG. 6 shows a vertical lamella structure of ananoline shape aligned in a guide pattern. It may be confirmed that thephase-separation of the block copolymer is realized such that the linearpattern is formed well.

Next, a pattern formation method using the described bottle-brush typeblock copolymer or the described linear block copolymer including therandom block will be described.

FIG. 7 to FIG. 10 are cross-sectional views of a coated substrateillustrating an exemplary pattern formation method.

Referring to FIG. 7, a mother pattern layer 200 comprising a materialfor forming a pattern is formed on a substrate 110. A neutralizationlayer 120 is formed on the mother pattern layer 200. The substrate 110can be a glass substrate or a silicon substrate. The neutralizationlayer 120 is a layer that does not have hydrophilicity orhydrophobicity, is chemically neutral (i.e. has a neutral charge), andincludes a self-assembled monolayer (SAM), a polymer brush, and a MAT(cross-linked random copolymer mat) or an organic monolayer includingthe MAT.

Although not illustrated, before the mother pattern layer 200 is formed,the surface of the substrate 110 may be pretreated using an acidsolution such as hydrofluoric acid (HF).

Next, a guide pattern GP is formed on the neutralization layer 120. Theguide pattern GP may be formed through a photolithography process usinga photoresist material. The guide pattern GP may be formed by firstforming a photoresist layer on the neutralization layer 120 and thenradiating light using a mask to develop the photoresist layer. The guidepattern GP can be formed by a process not limited to a photolithographyprocess, and may be formed by another method such as a nanoimprintprocess.

The guide pattern GP controls the directivity of a block copolymer to besubsequently formed. The distance between the guide patterns GP may beabout 1.5 μm or less. However, when the guide pattern GP is formed bythe photolithography process, the distance may be 1.5 μm or more inconsideration of a limitation of resolution of photo equipment.

Referring to FIG. 8, a polymer thin film 140 is formed by coating thedescribed bottle-brush type block copolymer or the described linearblock copolymer including the random block between the guide patterns GPby a spin coating method and the like. The polymer thin film 140 is apolymer where two different kinds of monomers are covalent-bonded. Thetwo different kinds of monomers have different physical and chemicalproperties. Accordingly, the first monomer has relative hydrophilicitycompared to the second monomer, and the second monomer has relativehydrophobicity compared to the first monomer.

Referring to FIG. 9, the substrate 110 including the polymer thin film140 is heat treated. The heat treatment process may be performed atabout 200° C. to about 300° C. under a N₂ or vacuum condition for about2 hours or more. Ultraviolet ray treatment may be performed instead ofthe heat treatment. After the heat treatment, the polymer thin film 140is phase-separated into the first block NB1 and the second block NB2.

The first block NB1 may be linearly formed, and the second block NB2,which is phase-separated from the first block NB1, is disposed adjacentto the first block NB1. In an exemplary embodiment of the presentdisclosure, the first block NB1 may include a polystyrene moiety (“PS”)and the second block NB2 may include poly(methyl methacrylate) moiety(“PMMA”).

In the present exemplary embodiment, a period T of a unit at which thefirst block NB1 and the second block NB2 are repeated may be about 100nm or less.

Referring to FIG. 10, the second block NB2 is removed. Accordingly, theguide pattern GP remains on the neutralization layer 120.

The second block NB2 may be removed through wet etching. For example, ifthe substrate 110 including the first block NB1 and the second block NB2is immersed in a solution including acetic acid and then subjected tosonication, only the second block NB2 is selectively removed. Unlikethis, the second block NB2 may be removed through dry etching. Forexample, after ultraviolet rays are radiated on the first block NB1 andthe second block NB2, only the second block NB2 may be selectivelyremoved through reactive ion etching (RIE) by a difference in etchingselectivity.

Next, by using the first block NB1 as a mask, the neutralization layer120 and the mother pattern layer 200 are etched to pattern the motherpattern layer 200.

Next, the first block NB1 and guide pattern GP are removed. For example,the substrate 110 including the first block NB1 and guide pattern GP maybe immersed in a solution including toluene or the like and thensubjected to sonication to remove the first block NB1 and guide patternGP.

FIG. 11 is a perspective view of a pattern formed by the patternformation method described in FIG. 7 to FIG. 10, and FIG. 12 is across-sectional view taken along the line XII-XII of FIG. 11.

The pattern illustrated in FIG. 11 and FIG. 12 may be a metal patternconstituting a polarizer. Referring to FIG. 11 and FIG. 12, the motherpattern layer 200 is patterned to form a linear lattice pattern 210including a first line 210 a and a second line 210 b on the substrate110.

The first and second lines 210 a and 210 b extend in the first directionD1 of the substrate 110. The second line 210 b may be disposed in thesecond direction D2 that is different from the first direction D1 of thefirst line 210 a. The first and second lines 210 a and 210 b may includealuminum, silver, platinum, or the like.

While this disclosure has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the disclosure is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A block copolymer comprising: a first blockrepresented by Chemical Formula 1; and a second block represented byChemical Formula 2:

wherein COM1 and COM2 are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 ishydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenylgroup, a is 1 to 50, R2 is hydrogen or an alkyl group with 1 to 10carbon atoms, and b is 1 to
 50. 2. The block copolymer of claim 1,wherein the block copolymer comprises a block represented by ChemicalFormula BC comprising a first block represented by Chemical Formula 1and a second block represented by Chemical Formula 2:

wherein COM1 and COM2 are independently selected from a polystyrenemoiety, polymethylmethacrylate moiety, polyethylene oxide moiety,polyvinylpyridine moiety, polydimethylsiloxane moiety,polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 ishydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenylgroup, x is 10 to 500, a is 1 to 50, R2 is hydrogen or an alkyl groupwith 1 to 10 carbon atoms, y is 10 to 500, and b is 1 to
 50. 3. Theblock copolymer of claim 2, wherein in Chemical Formula 1, COM1comprises a group represented by Chemical Formula 3, and in ChemicalFormula 2, COM2 comprises a group represented by Chemical Formula 4:

wherein Ph is a phenyl group and Me is methyl, n is 10 to 1000, m is 10to 1000, and * means a point of attachment.
 4. The block copolymer ofclaim 2, wherein the block copolymer is represented by Chemical Formula5:

wherein Ph is a phenyl group, Me is methyl, x is 10 to 500, y is 10 to500, n is 10 to 1000 and m is 10 to
 1000. 5. The block copolymer ofclaim 1, wherein the first block and the second block is connected toeach other randomly.
 6. A method of making a block copolymer,comprising: synthesizing the block copolymer of claim 2 in the presenceof a compound of Chemical Formula 6:

wherein OTBS is a tert-butyldimethylsilyloxy group, and a is 1 to
 10. 7.The method of claim 6, wherein the material of Chemical Formula 6 issynthesized based on Reaction Equation 1:

wherein TBSC1 is tert-butyldimethylsilyl chloride, and OTBS istert-butyldimethylsilyloxy group.
 8. The method of claim 5, wherein theblock copolymer is made by polymerizing a first macromer represented byChemical Formula 7 or Chemical Formula 7-1 and a second macromerrepresented by Chemical Formula 8 by a ring opening metathesispolymerization method:

wherein Ph is a phenyl group, Me is methyl, a is 1 to 10, n is 10 to1000, b is 1 to 10, and m is 10 to
 1000. 9. The method of claim 8,wherein the first macromer represented by Chemical Formula 7 issynthesized based on Reaction Equation 2:

wherein OTBS is a tert-butyldimethylsilyl oxy group, Ph is phenyl, and nis 10 to
 1000. 10. The method of claim 8, wherein the second macromer issynthesized based on Reaction Equation 3:

wherein Ph is phenyl, Me is methyl, OTBS is tert-butyldimethylsilyl oxygroup, and m is 10 to
 1000. 11. The method of claim 8, wherein a Grubbscatalyst is present during the polymerization of the first macromer andthe second macromer.
 12. The method of claim 8, wherein the firstmacromer represented by Chemical Formula 7-1 is synthesized based onReaction Equation 4:

wherein Ph is phenyl, and n is 10 to
 1000. 13. A pattern formationmethod comprising: coating the block copolymer of claim 2 on a substratecomprising a mother pattern layer to form a polymer thin film;selectively removing one block of a first block and a second block fromthe polymer thin film; and etching the mother pattern layer by using thepolymer thin film from which one block is removed as a mask.
 14. Thepattern formation method of claim 13, wherein the polymer thin film istreated with ultraviolet rays or heat.